There presently exist a variety of wire inserts for supporting coiled filament bodies in an electric incandescent lamp. See, by way of example, U.S. Pat. No. 3,403,280 to Cardwell for one form of filament support that is of relatively complex construction. The common state-of-art insert is mono-plane in geometry.
One drawback associated with a mono-plane insert relates to the need to form, usually by hand, one end of the coiled filament body so that it conforms with the geometry of the mono-plane insert. There is thus a labor step required in forming the coil end to conform it to the insert configuration. Furthermore, the forming of the coil body causes some distortion thereof that causes some degradation in lamp operating quality. By the term coil, when used singularly herein, is thus meant to define a coiled coil structure wherein the structure (a wire) is originally coiled to form an initial configuration (i.e., linear) and this element is thereafter coiled again to form a second, different configuration (i.e., as shown in FIG. 2A of the drawings).
As indicated previously, there are a variety of configurations of mono-plane inserts for incandescent coiled coils. One industry standard is referred to as the "shepherd's crook" insert, so named for the bend at the top of the insert. For one thing, this bend may cause a problem by engaging the inner surface of the lamp envelope at the dome portion thereof, in turn causing a jamming of the coil during assembly. Secondly, the bend at the top of the insert means that the coil body has to be formed thereto and thus undesirably distorted. Also, the "shepherd's crook" is not well adapted to the fabrication of miniature sized lamps. For some lamp designs employing reflectors, the envelope has had to be elongated to compensate for the "shepherd's crook" insert design. This thus makes it more difficult to optimize miniaturization of the lamp.
Another form of standard insert is one having straight, vertically-disposed legs both at the top and bottom thereof. This insert is also mono-plane and requires forming, thus distorting the coil body. There is also a further configuration of insert in which the standard straight leg insert has a ninety degree bend at the top at the long (upper) side of the insert. Again, this form of insert causes a significant deformation in the top turns of the coil body.
It is, believed, therefore, that an insert capable of overcoming the aformentioned disadvantages of known such components would constitute a significant advancement in the art.